“We've been admiring Richard Prince's work for a few years now. A week ago we approached him asking him to design a zero dollar bill, artistic money. He came up with a design over the weekend and we printed 42000 bills for the Primavera Festival performance.”

Conceptually, this probably has something to do with the name of their most recent album, Bankrupt!. Here's a brief video of what happened, plus another fake dollar detail shot: